I run several Perl dancer applications at the same time with the same user in FCGI mode (Apache). As I understand correctly, Apache (or any other webserver) will fork a new dancer application if the current one(s) are busy.
To ensure that no visitor is interrupted by the dancer shutdown I like to let dancer handles the current connection until it finished and then exit/last the process.
How to shutdown a Perl dancer application using kill signal HUP to perfom such nice shutdown?
To rollout a new version of a dancer application I use pkill -HUP perl as the dancer user to "shutdown" the processes. But currently (due to missing signal handler) it's more like shoot 'em down as of shutdown an application.
The solution by mugen kenichi works (starman):
If you are able to change your infrastructure you could try one of the plack webservers that support your need. starman and hyponotoad both do graceful restarts on SIGHUP
There are a few shortcoming regarding <% request.uri_base %> so we have to develop with hard coded URI paths. Not very handsome but necessary.